1. Field of the Invention
This invention relates to a method of making plastic identification cards, and more particularly to a method of making laminated identification cards of hard plastic with a photograph, a magnetic recording tape or the like interposed between the layers thereof.
2. Description of the Prior Art
Laminated plastic cards for identification use such as credit cards, membership cards, identification cards, bank account cards etc. are mainly composed of a pair of transparent plastic sheets and a white opaque plastic sheet interposed therebetween bearing on the surface thereof printed information such as the title of the card, the issue date, the name of the person, the expiration date term etc.
This kind of plastic card should preferably have identification means such as a portrait of the owner of the card. There have been two popular methods of preparing this kind of laminated plastic card including a portrait interposed between the layers thereof. In one of these methods of lamination adhesives are applied to the surfaces of the plastic sheets to be laminated. In the other lamination is accomplished by fusing the surfaces of the plastic sheets by heat.
The method of lamination using adhesives is disadvantageous in that the manufacturing cost is raised by the adhesive applying process and in that the life of the cards is limited to the life of the adhesives. The method of lamination by heating and fusing the surfaces of the plastic sheets is disadvantageous in that a high heating temperature is needed. When the plastic sheets are too much heated, the surface of the plastic sheet bearing printed information is softened and the printed information is deformed.
In the above described conventional methods, the plastic sheets are heated by heating pressure plates which work to heat the surface of the laminated plastic sheets from outside. These external heating methods usually heat the surface of the plastic sheets up to about 100.degree. C when adhesives are used and about 130.degree. to 150.degree. C when no adhesives are used. Therefore, it usually takes 30 to 60 minutes to complete the lamination. Thus as a practical matter, it is almost impossible by these methods to produce identification cards with a portrait interposed between the sheets thereof. If, in spite of the difficulties involved, a card with a potrait is prepared, the surface of the completed card is apt to swell in the area where the potrait is interposed. Further, it often happens that bubbles appear around the portrait interposed between layers of the laminated card.